Method of and apparatus for compressing and expanding elastic fluids



NOV. '12, 1929. K, fgr'u -r 1,735,477

METHOD OF AND APPARATUS FOR coMPREssme Anb'mrmmue ELASTIC FLUIDS Filed June 16, 1922 j 9 Sheets-Sheet 1 1,735,477 .maop OF AND APPARATUS FOR commssme AND sxrmnme ELASTIC mums N0v.12, 1929. K. E. STUART filed une 16, 1922" 9 Sheets-Sheet 2 'Noir. f2, 1929. K. E. STUART 1,735,477

METHOD OF AND APPARATUS FOR QOMPRES SI NG AND EXPANDING ELASTIC FLUIDS- 9 Sheets-Sheet Filed June 16, 1922 Nov.12,'l929. K. E. STUART 1,735,477

Immaon OF AND APPARATUS rowcournmssme AND Exrmnme mms'nc Fwms' Filed June16. 1922 I l 9 Sheets-Sheet 4 Nov. 12, 1929.

K. E. STUART j METHOD OF AND iAPPARATUS FOR COMPRESSING AND EXPANDING ELASTIC FLUIDS 7 Filed Ju e"16.1922 S -Shea tS-Sheet 5 Nov. 12, 1929. K, E, STUART 1,735,477

METHOD OF AND APPARATUS FOR COMPRESSING AND EXPANDING ELASTIC FLUIDS Filed June 16. 1922 S'SheetS-She et 6 K. E. STUART Nov. 12 1929.

METHOD OF AND APPARATUS FOR COMPRESSING AND EXPANDING ELASTIC FLUIDS Filed June 16. 1922 I 9 Sheets-Sheet 7 I Nov. 1 2, 1929. STUART 1,735,477 METHOD OF AND .QPPABATUS FOR COMPRESSING AND EXPANDING, ELASTICJFLUIDS Filed June 16. 1922 9SheetS-Sh9ef 8 Nov. 12, 1929. I s u RT 1,735,477

I METHOD OF AND APPARATUS FOR COMPRESSING AND EXPANDING ELASTIC FLUIDS Filed June 16. 1922 9 Sheets-Sheet 9 Patented Nov. 12, 1929 I UNITED STATES.

PATE T OFFICE KENNETH n. STUART, or mEmoN, PENNsYLvANIA, ASSIG-NOR To Tim STUART RE- SEARCH ENGINEERING CORPORATION, or NEWARK, NnwJERsEY, A CORPORATION OF DELAWARE METnon or AND ArrARATUs roa comranssmo ANn- EXPANDING ELASTIC mums Application filed June 16,

My invention relates to a method of and apparatus for compressing and expanding elastic fluid, for any suitable, purpose, but particularly for the production of power,

particularly by internal combustion, in or by rotary, as distinguished from reciprocating, structure.

In accordance with my invention, there are provided co-acting members or elements bearing in general the relationship to each other of a worm and gear whose axes of rota- I tion are at substantially right angles to each other, the worm having single or multiple helicoidal groove or grooves with which ooact pistons upona piston disk corresponding with gear teeth intermeshing with the worm, the pistons and grooves, together with ajsurrounding casing; forming one'or a series of compression or expansion chambers whose volume varies during revolution of the rotor structure.

In accordance with one of the aspects of my invention, an elastic combustible mixture, or an elastic component of a combustible mixture, 'is first compressed, either within the rotor structure, or independently thereof, and then caused to ignite withinv a combustion chamber, formed by the rotor groove,'pistons and easing as aforesaid, preferably at or adjacent the region of least orlesser diameter of the rotor structure, the pressure of the gases resulting. from combustion their effecting rotation of the rotor structure to produce power as the gases progressively expand as the volume of the combustion or expansion chamber progressively increases as the pistons progressively co-act with' the rotor groove of increasing diameter.

In accordance with another aspect of my invention, elastic fluidis compressed by introducing it into a chamber formed by a groove, pistons and casing,'as aforesaid, at p y or adjacent theend of greater or greatest diameter of the rotor structure, and by driving the structure from an external source of power causing the elastic fluid to traverse the groove in such direction that the chamber progressively decreases in volume.

A feature of my invention is the employmerit of a rotor increasing in diameter in both 1922. Serial No. sear/a0.

directions longitudinally from the region of A'further feature of my invention resides v in the provision of expanding ring packings in the casing-engaging surfaces of the rotor, in the rotor-engaging surfaces of the pistons on the piston disk, and in the casing-en'gag .ing surfaces of the piston disk, the grooves and pistons being I preferably, though not necessarily, semi-circular in shape,

A further feature of my invention resides in'the provision of lubrication for the piston disk and rotor by recourse to lubricant con,- tained in a reservoir through which the iston disk rotates and in so doing accumulates and transports oil from the reservoir in controllable quantity.

A further feature of my invention/resides in cooling the rotor, whether employed for compression or expansion, or both, by forming in it a passage or passages independent of 1ts groove or grooves and passing cooling medium through such pasage or passages;

and preferably, when the structure is employed as an internal combustion engine,-

passing the combustible mixture or a component-thereof through the rotor structure for cooling it in advance of introduction into the rotor structure, whereby regenerative cooling is effected in the sense that the heat units absorbed by the cooling medium are intrioduged into the rotor and usefully emo e A further feature ofmy invention resides in the employment of a blower or rotary pump movable with the rotor structure for passing through the rotor structure the aforesaid cooling medium, whether or not it be a combustible mixture or component thereof. A further feature of my invention resides 1n the employment of a pair or pairs of rotors rotating as a unit and so presented to each other that the effective axial thrust produced by one rotor of each pair is operative in a direction toward the neighboring rotor of the pair.

My invention resides in the method and ap paratus hereinafter described and claimed.

For an understanding of my method and for an illustration of some of the many forms my apparatus may take, reference is to be had to the accompanying drawings, in which:

Fig. 1 is a top plan View of a twin motor comprising two pairs of rotors.

Fig. 2 is a vertical sectional view, partly in elevation, taken on the line 2-2 of Fig. 1. Fig. 3 is a vertical sectional view taken on the line 33 of Fig. 1.-

Fig. 4 is a vertical sectional View, partly in elevation, taken on the line 44 of Fig. 1. Fig. 5 is an end elevational view of the blower.

Fig. 6 is a cross sectional view, partly in elevation, taken on the line 66 of Fig. 7. I

Fig. 7 is a side elevational view of a rotor. Fig. 8 is a fragmentary end elevational view of the hub structure of a rotor.

Fig. 9 is an edge view of the piston disk. Fig. 10 is' a side elevational view of the piston disk.

' Fig. 11 is a fragmentary sectional view, on enlarged scale, on the line 1111 of Fig. 10.

Fig. 12 is a fragmentary elevational view, on enlarged scale, of apiston element.

' Fig. 1-3 is a fragmentary sectional view, on

enlarged scale, taken Fig. 10.

Fig. 14 is a fragmentary elevational view of one of the elements of the piston disk.

Fig. 15 is a side elevational View, on enlarged scale, of an expanding packing ring of one of the pistons.

Fig. 16 is a cross sectional view, partly in on the line 13-'-13 of elevation, of the ring shown in Fig. 15.

- Fig. 17 is a side elevational view of one of the expanding packing rings co-acting be tween the piston disk and casing.

Fig. 18 is a cross sectional view, partly in elevation, of the ring shown in Fig. 17.

Fig. 19 'is a sectional View, on enlarged scale,-of a portionof the rotor structure and its expanding packing ring.

Fig. 20 is an elevational view of a portion of the sectional helicoidal expanding packing ring for the rotor. Fig. 21 is a longitudinal sectional view of a rotor structure providing unequal compression and expansion ratios. Fig. 22 is a graphic representation explanatgry of the pressure changes throughout. a

Fig. 23 illustrates a modified form of piston element.

Fig. 24 is a view, on enlarged scale, of the oil reservoir and lubricating means.

' posed, none, so far as I am aware, has proven commercially practical for the reason, as I- believe, that they have been either of an inherently unbalanced construction, 'or if balanced, they have been of such construction that it has been impossible to render them even approximately pressure-tight at the coaoting surfaces of the rotating elements. In

accordance with my invention, however, parrotating about axes substantially at right angles to each other.

The rotor B may be single-threaded or single-grooved, or, and preferably, as indicated, multiply or doubly-threaded or grooved, one of the two grooves being indicated at g and the other at g The grooves divided into two symmetrical halves 'bo ted to each other.

Longitu'dinally of the periphery of each of the ribs or threadsbetween grooves g and g is provided a slot or groove 1, Fig. 19, in which is disposed a metal expanding-packing ring or member 2, Figs. 6, 7 19 and 20, preferably divided into sections, 0

about one turn each, the sections being suitably overlapping, as by step joint, as indicated at 2 the depth of the ring diminishing or tapering from the end of'larger diameter to the end of smaller diameter. On 0 posite sides of the packing ring 2 within t e ribs or threads of the rotor R are provided oil grooves 1 The ring or member 2'forms a pressure-tight joint with the inner surface'of the casing C, which in effect forms the bear- 7 mg and support for the'rotor R which rotates ton disk P also bears and rotates uponthe from the c ambers of the first series.

halves of the casing C. intervene the metallic Between the piston disk P and the two,

expanding packing rings 3, Figs. 4, 17 and 18, each of triangular or tapered cross section, one side of the triangle bearing against the flat side face "of the piston disk while the other two sides are disposed in angular circumferentially extending grooves in the two halves of the casing C, theserings forming a pressure-tight joint between the rotating piston disk and the casing members C. The rings 3 are preferably of triangular cross section as describe'd,in order that the ring in 7 expanding under-its own bias causes a lateral movement of the ring against the side of the iston disk; a further advantage lies in the act that merely an apex of the ring '3is presented to the region-in which pressures obtain, with the result that they exert substantially no, force u on the ring.

Referring to igs. 9 to 14 inclusive, the piston disk P comprises the inner ring 4 disposed between the outer ring segments 5, 5, secured by screws 6 passing through both plates 5 and ring 4. he plates 5 have the substantially semi-circular outwardly projecting lugs 7 concentric with the substantially seml-circular recesses '8 in the ring 4.

There is accordingly formed outside ofeach recess 8 and between the lugs 7, 7 a substantially circular space within which is disposed a circular metallic piston element 9 secured in place by the screw 10 passing through the lugs 7, 7 and element 9, the screw bein suitably locked, as by pin 11. Between t e peripheral edges of the lugs 7, 7 and surrounding or embracing the 'piston element 9 is disposed a metallic expanding packing ring 12,

etween whose adjacent ends 13is. disposed the lug 14 on' the plate 4 for preventing creeping or turning of the ring 12. As indlcated in Figs. 11 and 16, the outer contour ofthe packing ring 12 is curved at 12,whereby substantially a perfect line contact is effected between each of the piston elements p and the surface of the grooves g and g in the rotor R. a

Referring to Figs. 1, 2, Band 4, there are formed and provided in opposite ends of each casing member 0 the intake 0 enings 15 and exhaust openings 16 communicating, respectively, with the circumferentially extending intake ports or passages 17 and exhaust ports or passages18, with which communicate at opposite ends of the rotor, during rotation of the rotor R, the rotor grooves g and g. The

outlets of the passages between vanes 36 deliver into' the volute discharge ports or passages'17 and 18 are formed in the substantially torroidal members 19 and 20, respectively.

The rotor chamber or casing is closed on the intake end by an end plate 21 having labyrinth grooves or rings 22 forming a joint with the end of the rotors Secured to the inside of each end plate 21 is a'member 23 whose outer surface conforms substantially with the shape of the inner surface of the .hollow rotor R and is spaced therefrom to form a passage 24 communicating with the opening or connection at 25 in the member 21. The exhaust end of each rotor casin is closed by a member 26, each having a la yrint'h groove joint with the exhaust end of the rotor. I

The adjacent casing end closingmembers 26, 26 form a housing for a pinion 27 meshing with and driving the main car 28 secured upon the main shaft 29. T e pinion 27 is.

secured upon the bearingles's stub shaft 30 so i carrying at each end keys 31 enga 'ng in keyways 32, Fig. 8, in the hubs 33 o the rotors.

The shaft 30 continues beyond the hub 33 in a portion 34 terminating adjacent the end of the member 23 and havin an outer surface spaced from theinner sur ace of the rotor to form a continuation of the passage 24, which communicates throug'h'the passa es 35 in the rotor hub' 33 with the s aces vanes 36 of arotary or tur ine compressor or blower whose rotatable body 37 carrying the vanes 36 is secured upon and rotates with the shaft 30 and the rotor R. The

e blower passage 38 formed in the end casing closure member 26 and communicating with the discharge pipe 39, which connects with the intake opening 15.

The rotor hub 33 has a free sliding fit upon the shaft 30, and has a conical portion coacting with the conical shoulder upon the shaft 30, whereby the shaft 30 and rotor R are brought into true concentric relation. In an arrangement 'such as indicated in Fig. 3 where two-rotor structures co-act with the same shaft 30 and pinion 27 the axial or longitudinal thrusts produced by the rotors are er'ipheral tli etween the both exerted toward the pinion 27, whereby these thrusts assist in centering and holding the rotor and shaft 30concentric, the grease packings 30 bein either thrust or radial load, as shown more clearly in Figs. 27 and 28. It will be seen that labyrlnth grooves 30 are provided in the shaft 30, and these grooves arefitted closely by corresponding ridges in the grease packing 30. Radial clearance is provided, however, s0 that the grease packing 30 can give no support to. the shaft 30 within the limits of any possible displacement of the latter, as through wear. Also, the grease packing 30, is free to slide longitudinally in its supporting casing 26 so that itcan take no thrust. 30 is a felt washer which, because of its elasticity, is likewise incapable of constricting the freedom of the shaft 30 and clearance is provided between the casing wall 26 and the gear 27 for the same reason. The grease packing 30 l is metallic and preferably of Babbitt metal.

' manifold pipe 42 which in turn communicates with the aforesaid opening or inlet communicating with the passage 24 within the rotor and 1n turn communlcatlng w1th the blower 36, 37, which in turn delivers through the discharge casing 38 and pipe 39 with the intake opening 15. The exhaust opening 16 communicates with the exhaust pipe 43 communicating with the exhaust manifold 44.

Referring to Figs. 3, 4, 24, 25 and 26, the

structure for lubricating the piston disk P.

and by it the rotor R 'comprises a chamber or reservoir 45, to which oil is supplied by the pipe 46. I The reservoir is formed by extensions upon the casing members C and the attached closing wall members 47. A portion of the casing members C, C which houses or supports the piston disk P extends through the reservoir 45, and on each side is provided a gauze screen 48 through which the oil must pass on its way to the disk P. That portion of the casing members C, C which is immediately adjacent or houses the piston disk P is cut away at 49, forming a passage to establish communication between the reservoir between screens 48-and the piston disk P which is wet with oil as it revolves. is formed a groove 50 in a face of one of the casing members C which lies against a lateral face of the revolving piston disk P, the piston disk forming one wall of the channel or groove. The oil'adhering to the piston disk is wiped off by the edge of the casing member C, with the exception of that oil which is removed from the lateral face of the piston disk and passes through the groove orchannel'50 to theexterior of the piston disk, to which it adheres, and is thereby carried around and into contact with the rotor R for lubricating the engaging surfaces of piston disk and rotor. By this structure the quantity of oil fed to the contacting surfaces of rotor'and piston disk is a function of the cross section of the groove 50, the speed of the pistondisk P and theangle of inclination of the groove 50, and is independent of the viscosity and depth-of oil. 7 f

' he modeof operation is as follows:

Considering a single unit comprising one .rotor R and piston disk P, the .carbureted mixture. is delivered from the carbureter 40 throughmanifold 41 and pipe to the opentending port or passage 17, from which it passes into a rotor chamber formed by two pistons 39 upon the disk P, a rotor groove and the surrounding casing. As the rotor and piston disk revolve, the volume of such chamber progressively diminishes toward the region of. smallest diameter of the rotor, the combustible mixture undergoing compression, in thepresent illustration, with a compression ratio of approximately four. The charge in the chamber is then ignited by spark produced by the spark plug51, with resultant rapid increase in gaseous pressure within the chamber exerted upon its walls. That wall of the groove which has greater diameter has exerted thereon a pressure in excess of that exerted upon the wall of smaller diameter, and such excess pressure is exerted in a direction having a torque-producing component which-causes rotation of the rotor structure. In the example illustrated, the ratio of expansion after combustion is approximately four, and the gases are finally exhausted into the circumferentially extending passage orport 18 and discharged through the opening 16 and exhaust pipe 43' to the exhaust manifold 44.

Accordingly, the combustible mixture is first compressed by the rotor, and after ignition at the point of maximum compression the gases expand and produce rotation, as stated, the rotor structure as a whole performing the dual function of compression of mixture or charge and expansion of mixture or I charge after ignition to produce power. There As the rotor revolves, it causes rotation of the piston disk P, both rotor and piston disk bearing and rotating upon the casing members, without recourse to shafts for either of them. The power developed by the rotor is transmitted to shaft. 29 through pinion 27 and gear 28, and the load is driven by shaft 29.

The rotor chamber is cooled in any suitable Way, as by the heat radiating fins 52, or in lieu of them may be employed'a water jacket, as well understood in the internal combustion motor art.

The rotor is interiorly cooled by the com bustible mixture delivered as aforesaid to the opening 25-and flowing through the passage 24, one wall of which is the stationary member 23 and the other the inside wall of the rotor. The cross section of the passage 24 diminishes from its inlet to the-point or region of smallest diameter of the rotor, and in consequence the velocity of the mixture increases from the inlet 25 to the region of smallest diameter of therotor, abstracting heat from the rotor walls for cooling purposes. By this arrangement, the velocity of the cooling nnxture 1s a maximum where the maximum rotor temperatures exist, thereby producin most effective cooling. .The heat abstracte from the rotor'structure assists .also in vaporizing the gasolene or other fuel in the in again diminishes in velocity, in pressure by the blower 36, 37, if the same be used, and delivered through pipe 39 to the intake opening 15 communicating with the intake port or passage 17 communicating with the inlet end of the compressor portion or end of'the rotor.

The cooling system is regenerative in the sense that heat energy abstracted from the rotor structure by the ingoing mixture is largely conserved, since it is present in the mixture when delivered into the rotor structure and is recovered in part as increased power produced by the rotor in the succeeding combustion and expansion period.

From another aspect, the above described mode of cooling the inner walls of the rotor may be looked upon as a mode of transferring heat from the inner rotor walls to the exterior air or water jacket cooling system by first reintroducing heat into the working chambers of the rotor.

It will be understood that the cooling may be effected by any other medium than the ingoing mixture. For example, the pipe &2 may connect directly with the intake opening 15, the opening 25 may communicate directly with atmosphere, and the discharge casing 38 of the blower may deliver directly to atm'osphere. En'such case a current of air will be drawn through the rotor, cooling the same, and again discharged to atmosphere.

As indicated in Figs. .1, 2, 3 and i, a plurality of rotor-piston-disk units may be combined' to form a multiple unit motor.

In the example illustrated, two rotors drive one and the same pinion 27, being disposed on opposite sides thereof, the grooves of one rotor having right hand pitch while the grooves of the other have left-hand pitch,

. whereby both. rotate in the same direction and exert their axial thrusts toward each other or the pinion 27 and thereby effect axial thrust balance and centering of the rotors withrespect to their shaft 30.

As indicated, two rotor pairs are combined, the pinions 27 of the two pairs both co-aeting with and driving the main gear 28 upon the main shaft 29. This arrangementeifects a construction which is lighter in weight, the same main gear 28 servin as well for a plu-' rality of pairs or units as or a single pair or trated, may be relatively unit. Furthermore, the arrangement is short as regards axial length and better suited to the chassis of motor vehicles, as automobiles, aeroplanes, etc.

Upon the main shaft is secured the fly wheel W, which for a combination such as'llluslight, since in each rotor there are produced overlapping torque impulses, and the torque impulses of the different pairs also overlap. The torque impulses of the two rotors of a pair, however, are 'in phase with each other, whereby the axial thrusts are in phase or simultaneous. Furthermore, the mass or inertia of the rotor elements themselves is considerable, thereby lessening the necessity for weight in the fly wheel W.

Upon the fly wheel W may be formed the gear teeth 53, with which may mesh a pinion,

as of a Bendix drive or the like, for cranking the engine by an electric motor supplied by current from the vehicle storage battery.

The battery may be charged from the dynamo-electric generator G'whose armature and the cooling fan F are driven by belt 54. driven from the main shaft 29, which latter may also be provided with a jaw structure for hand cranking purposes. f

The electric ignition may be supplied by any suitable system. For example, an induction coil may be supplied by current from the storage battery (not shownfor generator igniter structure I whose re at-ively movable contacts are operated by a cam or rotatable element driven by the shaft 56 driven by the .bevel gear 57 meshing with and driven by.

the bevel gear 58 secured upon the main shaft 29. The high tension terminal of the second ary winding of the induction coil may connect to the central distributor contact 59, while each of the distributing terminals 60 will connect with two serially related spark plugs 51 for each pair of rotors R. The arrangement is preferably such that for each revolution of the rotor there is a spark'produced for each of the two chambers formed by the two rotor grooves. In other words,

,G, and the current interru'pyed by the usual considering a single rotor groove, there is produced a single spark per revolution, since for each revolution a chamber containing compressed combustible mixture reaches the region of smallest diameter of the rotor and is ready for ignition or explosion. Where, as indicated, there are two grooves and two series of chambers in operation, there will accordingly be two ignition sparks necessary per revolution of the rotor and timed 180 degrees from each other. Inasmuch as it is desirable that the axial thrusts of the two rotor structures of a pair be simultaneous, the igniting sparks for the two rotors of a pair are timed to occur simultaneously.

The time of ignition may be advanced and retarded by rotating the igniter casing I, as

well understood in ordinary ignition practice. This may be effected by connectingthe lever 61, attached to the igniter caslng, through suitable mechanical connections with a lever upon the steering wheel column or located at any reach of the operator.

other suitable point within The main shaft 29 may drive any suitableload, as a stationary load or a movable load in equal, and that the ratio of compression may, be greater than the ratio of expanslon, or

vice versa. I

In Fig. 21 there is shown a rotor structure in which the length of each groovetothe left side of the region or point of minimum rotor diameter, indicated by the line 63, is less than the length of the same groove to the right of .tion to the right for either expansion or the region 63. The portion of the roto'r to the left of the point 63 may be employed for either compression or expansion, and the porcompression. Preferably, however, the portion having the shorter groove length, that to the left of the point 63, is employed for com pression, while the section having greater groove length is used for expansion In the example illustrated, the ratio of compression is of theorder of four, while the ratio of ex pansion is of the order of five or six.

Referring to Fig. 22, there is illustrated a conventional or typical pressure-volume diagram'or-card of an internal combustion engine operating upon the so-called Otto cycle. The abscissae are volumes, and ordinates pressures. The volume (5 represents clearance, 1)

represents the maximum volume at the moment of exhaust in the case of equality of ratios of expansion and compression with wide open throttle, while 0 represents the maximum volumeat the moment of exhaust in the case where the ratio of expansion is greater than the ratio of compression under like circumstances of wide open throttle. For the case of equality of ratios of expansion and compression the ratio of expansion or ratio of compression is expressed by the ratio of the volume I) divided by the volume a; and for the second-case where the maximum volume at the moment of exhaust is represented by c, the ratio of compression is 6 divided by a as before, but the ratio of expansion is the volume 0 divided by the volume a and is greater than the ratio" of compression. As indicated by the diagram, with equal ratiosof compresion and expansion, exhaust takes place when the gases within the expansion chamber are still at relatively high pressure, and there is accordingly relatively greater waste than when the ratio of expansion is greater than the ratio of compression. A cycle such as that having length I) is obtainable by a rotor in described, either the so-called Otto or Diesel cycles may be employed. .The mode of operation described involving the introduction and compression of a combustible mix ture followed by ignition corresponds with the Otto cycle. It will be understood, however, that in lieu of introducing a mixture of air and fuel into the rotor structure, simply air may be introduced and compressed, and

'when at maximum compression, fuel may be injected as in the Diesel reciprocating engine, in which case ignition will automatically occur or may be aided or induced by spark. For such operation upon the Diesel principle, there may be supplied in lieu of or adjacent the spark plug 51 a fuel or oil injector of any suitable type.

While the compression hereinbefore referred to is that of a combustible charge or a component thereof for an internal -combustion engine, it will be understood that a rotorpiston-disk structure may be employed for compressing any elastic fluid, as air or gas, for any suitable purpose, by introducing the elastic fluid at the end of the rotor having greatest diameter, with resultant compression as thefcharge is advanced to the region or point of smallest rotor diameter at which the rotor may terminate and the compressed elastic fluid discharged to storage or other'point of use. In such case, the rotor is driven by an external source of power, as an electric motoror equivalent, while in the foregoing description of an internalcombustion motor the expansion portion of the rotor produces power, some-of which is consumed in com-z pressing the charge in the other rotor section.

While in the foregoing description the rotor grooves and piston elements have been referred to as of circular contour, itwill be understood that they may be of any other suit-- able contour. From the standpoints of efiectiveness in operation and simplicity and cheapness of construction, it is preferred that the groove and piston contours be smooth curves without angles, corners or abrupt changes of curvature. For example, the groove and piston contours may be elliptical, parabolic, hyperbolic, etc. In Fig. 23 ellipticalpiston elements are shown, the minor axis of the ellipse being radial of the piston disk I, though it will be understood if preferred, that the major axis may be radial. With the minor axis radial, as illustrated, there follows the advantage thatthe cross sec tion of the co-acting elliptical rotor groove may be of desired magnitude with relatively smaller depth, whereby the minimum diameter of the rotor may be carried to smaller limits without sacrifice of tion.

As illustrated inFig. 4, the casing C enclosing the portion of .the rotor R of minimum diameter is provided with an opening a for ignition purposes, the circumferential width of t-he'opening a being to such extent limited that communication betweenv neighboring groove cross sec- .rotor grooves or between neighboring turns or convolutions of a single rotor groove is prevented. For example, the circumferentialextent of the aperture is made, as indicated, less than the circumferential width of the rotor thread or rib between grooves or between neighboring convolutions of a single groove. Into the aperture 0, or to a position adjacent the edge of the, aperture 0,

extends the insulated electrode or spark ter-' minal 51 of the spark plug- 51, which is threaded into the interiorly threaded extension 0 upon. the casing C.

What I claim is:

1. An internal combustion motor comprising a rotor having a groove, a relatively stag5 tionarycasing member forming a wall of said groove, rotary structure co-acting with said rotor and its groove to intercept a portion of "said groove to form a chamber whose volume progressively diminishes and then increases, means for delivering to said chamber a combustible mixture for compression therein,

' means for igniting said'mixture in said chamber after'decrease in volume of said chamber.

and means permitting exhaust from said chamber after said' chamber has increased in volume.

2. An internal combustion motor comprising a rotor having a groove, a relatively stationary casing member forming a wallof said groove, rotary structure co-acting with said rotor and its groove to intercept serial- 1y disposed portionsof said groove to form a series ofchambers each of which progressively diminishes and increases in volume, means for delivering to said chambers 111 successlon 'a'combustible mixture for compressiontherein, means for igniting said mixture in each of said chambers after 1ts decrease 1n volume, and means permitting exhaust from said chambers in succession after their ncreaseinvolume.

3. Apparatus for varying-the volume of elastic fluid comprising a rotor having roove-forming thread structure, a casing ".orming a gr'oove wall upon which said thread structure rotates and bears and con stitutingthe bearing for said rotor, and

' rotary structure co-acting witlisaid rotor and 1 elastic its groove to intercept a portion of said groove to'form a chamber of varying volume.

'4. Apparatus for varying the volume of groove, a relatively 'stationarv casing form-- ing a wall for .said groove, shaftlessirotary structure co-acting with said rotor and its 1 structure.

uid comprising arotor' having a;

. expansion ring tween said lugs.

groove to intercept a portion ofsaid groove to form a chamber of varying volume, and

casing structure 11 'onwhich said rotary structure rotates an bears,sa1d casing structure constlt-utmg the bearing for said rotary 5. Apparatus for varying the volume of elast1c fluid comprising 'a' rotor having I groove-forming thread structure, casing structure forming a groove wall upon which said thread structure rotates and bears and constitutingthe bearingfor said rot0r,'and shaftless rotary structure co-acting-with said rotor and its groove to intercept a portion of said groove to form a chamber of varying volume, said casing structure upon which said rotary structure rotates and bears constituting the bearing for said rotary struc ture.

\ 6. Apparatus for varying the volume of elastic fluid com rising a rotor having groove-forming t read structure, structure surroundng said rotor and encasing gaged by said thread structure, an oil groove extending longitudinally of said thread structure in its casing-engaging surface, and rotatable structure co-acting with said rotor and its groove.

7. Apparatus elastic fluid comprising a grooved rotor, a casing forming a wall for the rotor groove, and, co-acting rotatable structure comprising piston elements co-acting with the rotor groove, and an expansion packing member;

in the periphery of each piston'element, said packing member having its external surface 'so formed as to effect substantiallya line contact with said rotor.

8. Apparatus for varying the volume of elastic fluid comprising a grooved rotor, a

coacting rotatable structure comprising piston elements co-acting with the rotor groove,

and anexpansionpacking member in the periphery of each pistonelement, said packingfimember having a curved outer surface whereby substantially line contact is eflected with said rotor.

9. Piston disk structure comprising members spacedfrom each other and having lugs forming piston elements and an expansion ring disposed between said lugs.

10. Piston disk structure comprising membersspaced from each other and having lugs .forming piston elements, a disk disposed befor varying the volume of 108 casing forming a wall for the rotor groove,

supporting member having disposed 111 said recess and each other by said supporting member and having lugs formlng piston .elements, said etween said lugs, and an expans on ring embracing said disk.

13. Plston d1sk structure comprlsmg a supporting member, members spaced from each other by 'said supporting member and having lugs .for'mmg plston elements, said suporting member havlng a recess, a CIICllIIlerentially incomplete expansion ring disposed in said recess between said lugs, and a pro]ection on said supporting member extendmg into the space between the ends of said ring.

I 14. Piston disk structure comprising a supporting ring, members spaced from each other by said supporting ring and having lugs forming piston elements, said members divided circumferentially into sections and secured to said supporting ring.

15. Apparatus for'varying the volume of elastic'fluid comprising a, grooved rotor, a: co-act'ing rotary structure having piston elements .co-acting with the rotor groove, a casing surrounding said rotor and rotary structure, and ring structure forming a packing between the co-acti-ng surfaces of said casing and said rotary structure.

16. Apparatus for expanding or. compressingelastic fluid comprising a grooved rotor, a co-acting rotary structure having piston elements co-acting with the rotor groove, a casing surrounding said rotor and rotary structure, and ring structure forming a packing between the co-acting surfaces of said casin and said rotary structure, said packing rlng having tapered cross section J 'liaving diflerent faces presented, respectively, to said rotary structure and said casing.

'17, Apparatus for expanding or compressing elastic fluid comprising a grooved rotor, a co-acting rotary structure having piston elements co-acting with the rotor groove, a casing surrounding said rotor and rotary structure, said casing having a groove of tapered cross section'concentric with said rotary structure, and a packing ring disposed in said groove and having a face contactwith said rotary structure.

18. Apparatus for expanding'or compressing elastic fluid comprising a grooved rotor, a co-acting rotary structure having piston elements co-acting with the rotor groove, a

casing surrounding said rotor and rotary structure, and a circumferentially incomplete expansion ring forming a packing between said casing and said rotary structure.

' '19. A member for acking a piston disk 7 comprising a. circum erentially incomplete expansion ring-having a face adapted to engage'the lateral face of the piston disk.

20,-A member for packing a piston disk a recess, a disk comprising acircumferentially incomplete. expansion ring having tapered cross sec tion and adapted to engage a lateral face of the piston disk.

21. In apparatus of the character described, the combination with a grooved rotor, of a co=acting rotary structure having piston elements co-acting with the rotor groove, and a lubricant reservoir through which said rotarystructure passes. v 22. In apparatus of the character described,

the combination with a grooved rotor, of a groove, said rotor and rotary structure rotating about axes which are non-parallel and non-intersecting, said rotor having an interior passage diminishing in cross section to a region adj acent the minimum diameter of said rotor, and means for passing cooling medium through said passage.

24. In apparatus of the character described,

the combination with a grooved rotor changing in diameter longitudinally of its axis of rotation, of co-acting rotary structure having piston elements co-acting with the rotor groove, said rotor being hollow, means 'disposed within said rotor forming with its interior wall a passage diminishing in cross section-to a re 'on adjacent the minimum diameter of sai ing cooling medium through said passage. I 25. An internal combustion motor comprising a grooved rotor diminishing in diameter longitudinally of its axis of rotation, of co acting rotary structure having piston elerotor, and means for pass ments co-acting .with the rotor groove, said I rotor and rotary structure rotating about axes which are non-parallel and'nominters'ecting, means for initiating combustion of a combustible mixture in said. groove adjacent the region of'minimum diameter of said rotor,

said rotor having an interior passage diminishlng 1n cross section to said region ad acent thevmlnimum. diameter of said rotor,

and means for passing cooling medium I through said passage.

26. An internal combustion mo-tor comprisinga ooved rotor diminishing and then ncreasmg in cross sectionlongitudinally of ltS axis of rotation to form compression and expansion sections, rotary structure having piston elements co-acting with the rotor groove, said rotor-having an interior passag'e sio'n sections, rotary structure having PIS:

. diminishin and then increasinfiin diameter ing a ing a grooved rotor diminishing and then in-' piston 'el groove, a relatively stationary casing sura wall-for theirotor groove,

ing projecti 28. :An internal combustion motor COIIIPIlS-J substantia ylin accord with't e change in diameter of said rotor, and means for introducmg cooling mediuminto. said passage to flow in a direction from the-compression to the expansion'section' of said rotor.

27. n internalcombustion'motor comprisooved rotor diminishing and then increasing in diameter longitudinally of its axis of rotation to form compression and expansion sections, rotary structure having ments co-acting with the rotor rounding and fitting the rotor and forming and heat radiatns on the exterior of said casing.

ing-a grooved rotor diminishing and then increasing in diameter longitudinally of its axis ofrotation to form compression and expanton elementscosacting with the rotor groove,

a relatively stationary casing surrounding. and fitting the rotor and-formin a 'wall for the rotor groove, and heat radiatin disks on the exteriorof said casing space longitudinally-of said rotor.

'29. An internal'combustion motor compriscreasing-in diameter longitudinally of its axis of rotation to form compresslon and expan-' sion sections, rotary structure having piston elements co-acting with the rotor groove, a

'- ton elements co-acting with .respect to each thrusts of each is in a tors,

relativel stationary casing surrounding and fitting t e rotor and forming a wall" for the rotor groove, .and heat radiating disks on the exterior of said casing spaced from each other longitudinally of said rotor, said disks projecting to greatest distance from said casing adjacent the region of minimum diameter of said rotor.

'30. An internal combustion motor comprising a grooved rotor diminishin and then increasing in diameter longitu inally of its axis of rotation to form compression and exrotory structure having piswith the rotor groove, and annular chambers adjacent opposite ends of said rotor. communicating, respectively, with the inlet of the compression and outlet of the expansion sections of said rotor.

31. In apparatus of the character de-- pan'sion sections,

scribed, a plurality of grooved co-axial rotors, a rotating structure for eachrotor havmg piston elements co-acting with the groove of said rotor, said rotors being so disposed direction toward the other rotor. i

32. In apparatus of the character described, a plurality of a rotating structure foreach rotor having piston elements co-acting 'with the groove of said rotor, saidrotors' rotating in the same direction and having their grooves pitched in groove,

other that the axialgrooved co-axial roopposite senses and each rotor exerting an axial thrust directed toward the other rotor. 33. In ap aratus of the character described, a,p urality of grooved co-axial rotors, a-rotatmg structure for each rotor having piston elements co-actin-g with the groove of said rotor, a casing for each rotor constitutlng a bearing therefor 11 on which said rotor bears androtates, an a bearingless shaft connecting neighboring of said rotors. 34. In apparatus -of the character ,de-

scribed, a plurality of grooved co-axial-ro- 4 tors, a rotating structure for each rotor having piston elements co-acting with the groove of said rotor, a casing tuting a bearing therefor upon which said rotor bears and rotates, a bearingless shaft connecting neighboring of 'saidrotors, said shaft having a and each rotor having a'tapered portion coacting with the adjacent tapered portion of for each rotor consti tapered portion for each-rotor,

said shaft for centering said shaft and rotor with respect'to each ot er. 35. In apparatus of the character described, a plurality of grooved co-axial roa tors, a rotating structure for each rotor havelements co-acting withthe groove ing piston a casing for each rotor constiof said rotor,

tuting a bearing therefor upon which said ro-- tor bears and rotates,-a bearingless shaft connecting neighboring of said rotors, a gear on said shaft, and a second gearmeshing with said gear.

"36. In apparatus of the character described, the combination with a pluralityof grooved co-axlal rotors, arotating structure for each rotor having p1ston elements co-acting with the groove of said rotor, a shaft con- 7 necting said rotors,'a gear on said shaft, and a second gear meshing with said gear.

37. In 'ap aratus of the character described, a p urality of groups of co-axial grooved rotors, rotor having piston elements co-actin with the rotor roove,-a gear connected to t e Totors of eac group, and a gear common to said gears and meshing therewith.

38. An internal combustion motor comprising a grooved rotor, rotary structure having piston-elements co-aoting with the rotor a casing member-surrounding the rotor and forming a wall of the rotor groove, said casing member-having an ignition aperture whose extent is less than the distance between neighboring grooves, and a spark a rotating structure for each plug fixed to-said casing adjacent said apera casing member surrounding the ro- I forming awall of the rotor groove,

fixed to said casing adjacent said. aperture and having an electrode extending into said.

-.-'chamber, and simultaneously expandingthe as and increasing the length of said champrising a grooved rotor diminishing and their increasing in diameter longitudinally of. its

aperture and spaced from the wall thereof. f.

40. An internal combustion motor come axis of rotation to form compression and expansion sections, a relatively stationary casing forming a wall of said groove, rotary piston elements co-acting with the rotor groove in said compression section and thereafter in said expansion section to form a .chamber which diminishes and then increases 1n volume, means 'for effecting in said chamber while in said compression section a combustible mixture, means for causing combustion in said chamber after it has decreased in volume, and means permitting exhaust from said chamber after it has traversed said expansion section. i

41. An internal combustion motor comprising a grooved rotor diminishing and then increasing in diameter longitudinally of its axis of rotation to form compression and expansion sections, a relatlvely stationary casing forming a wall of said groove, rotary piston elements co-acting with the rotor groove in said compression section and thereafter in said expansion section to form a chamber which diminishes and then increases in volume, said piston elements and said rotor rotating about axes which are non-parallel and non-intersecting, means for effecting in said chamber while in said compression sec-- tion a combustible mixture, means for causing combustion in said chamber after it has decreased in volume, and means permitting exhaust from said chamber after it has-traversed said expansion section.

42. An internal combustion, motor comprising a rotor having a plurality of grooves and diminishing and then increasing in diameter longitudinally of its axis of rotation to form compression and expansion sections,

a relatively stationary casing forming a wall of said grooves, rotary'structure having plston elements engaging in said grooves to form chambers whose volume progressively diminishes and then increases, said chambers of the different grooves passing the'r egion of minimum. diameter of said rotor in' succession, means for delivering to said chambers While in said compression section at least one component of a combustible mixture'for compression in said section, means for causing combustion in said chambers afterdecrease in volume, and means permitting exhaust from said chambers after traverse of said expansion section.

'43. The method of producing power by internal combustion, which comprises introducinga combustible mixture or component thereof into a helicoidal chamber, diminishing the length of said chamber While rotat ing to decrease its volume and efli'ect compression', thereafter causing combustion in said chamber to effect gas pressure to rotate said er to increase its volume. v 44. The method of producing power by internal cembustion, which comprises introberto increase its volume, and passing com bustible mixture or com onent thereof in contactwith a wall of sai chamber on the in 'terior of the helicoid in'advance of said compression in said chamber.

45. The method of producing power by internal combustion, which comprlses rotating a helicoidal groove disposed at diminishing and then increasing distances from the axis of rotation, intercepting a portion of the groove to form a chamber which-decreases and .then increases in volume, introducing a combustible mixture or component thereof into said chamber to effect compression during decrease in volume of said chamber, thereafter causing combustion in said chamber to effect gas pressureproducing rotation of said chamber, and simultaneously expanding the gas and increasing the volume of said chamof rotation, intercepting a portion of the groove to form a chamber which decreases and then increases in volume by changing the length of the chamber, introducing a combustible mixture or component thereof into said chamber to effect compression during decrease involume of-said chamber, thereafter causing combustion in said chamber to effect gas pressure producing rotation of said chamber, and simultaneously expandingthe gas andincreasing the volume ofsaid chamber. 47. Apparatus for varying the volume of elastic fluid comprising a pair ofco-axial rotors spaced longitudinally from each other, each having groove-forming thread structure, a casing for each rotor forming a groove wall upon which the thread structure of the rotor rotates and bears and constituting the bearing for the rotor, rotary structure 00-- acting with each rotor and its groove tointercept a portion of, said groove to form a chamber of varying volume, and shaft structure secured to and supported solely by said rotors. In testimony whereof I have hereunto set my signature this 14th day of June, 1922.

KENNETH E. STUART. 

